Shedding light on dark DNA Most textbook definitions of evolution state that it occurs in two stages: mutation followed by natural selection. DNA mutation is a common and continuous process, and occurs completely at random.
The average adult only eats 15 grams of fiber per day. Women need 25 grams of fiber per day, and men need 38 grams per day, according to the Institute of Medicine.
Women need 25 grams of fiber per day, and men need 38 grams per day, according to the Institute of Medicine. Eating more plant foods -- vegetables, beans, fruit, whole grains, and nuts -- is the best way and is one of the major recommendations from the U.S. government's 2010 Dietary Guidelines.